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| Titel |
Effects of an iron-light co-limitation on the elemental composition (Si, C, N) of the marine diatoms Thalassiosira oceanica and Ditylum brightwellii |
| VerfasserIn |
E. Bucciarelli, P. Pondaven, G. Sarthou |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 7, no. 2 ; Nr. 7, no. 2 (2010-02-16), S.657-669 |
| Datensatznummer |
250004494
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| Publikation (Nr.) |
 copernicus.org/bg-7-657-2010.pdf |
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| Zusammenfassung |
| We examined the effect of iron (Fe) and Fe-light (Fe-L) co-limitation on
cellular silica (BSi), carbon (C) and nitrogen (N) in two marine diatoms,
the small oceanic diatom Thalassiosira oceanica and the large coastal species Ditylum brightwellii. We showed that C and
N per cell tend to decrease with increasing Fe limitation (i.e. decreasing
growth rate), both under high light (HL) and low light (LL). We observed an
increase (T. oceanica, LL), no change (T. oceanica, HL) and a decrease (D. brightwellii, HL and LL) in BSi per
cell with increasing degree of limitation. The comparison with literature
data showed that the trend in C and N per cell for other Fe limited diatoms
was similar to ours. Interspecific differences in C and N quotas of Fe
limited diatoms observed in the literature seem thus to be mostly due to
variations in cell volume. On the contrary, there was no global trend in BSi
per cell or per cell volume, which suggests that other interspecific
differences than Fe-induced variations in cell volume influence the degree
of silicification. The relative variations in C:N, Si:C and Si:N versus the
relative variation in specific growth rate (i.e. μ:μmax)
followed the same patterns for T. oceanica and D. brightwellii, whatever the irradiance level.
However, the variations of C:N under Fe limitation reported in the
literature for other diatoms are contrasted, which may thus be more related
to growth conditions than to interspecific differences. As observed in other
studies, Si:C and Si:N ratios increased by more than 2-fold between 100%
and 40% of μmax. Under more severe limitation (HL and LL), we
observed for the first time a decrease in these ratios. These results may
have important biogeochemical implications on the understanding and the
modelling of the oceanic biogeochemical cycles, e.g. carbon and silica
export. |
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